Apparatus and method for communicating stop and pause commands in a video recording and playback system

ABSTRACT

The invention provides a video recording and playback system comprising a video storing and retrieving device coupled to a video display device so as to provide the video display device with frames of video data for display. The video storing and retrieving device includes at least one memory capable of storing frames of video data, comprising packets according to a format. The format provides a trick mode indicator. A controller is coupled to the memory and controls operations of the memory. A user control device is operable with the controller to allow a user to communicate stop and pause commands to the controller. A processor cooperates with the controller so as to clear the trick mode indicator of at least one retrieved packet in response to the stop command. The processor cooperates with the controller to set the trick mode indicator of at least one retrieved packet in response to the pause command.

BACKGROUND OF THE INVENTION

The present invention generally relates to controlling video playbacksystems, and more particularly, to a method and apparatus forcommunicating stop and pause commands for controlling viewing of movingpictures.

In recent years, systems for sending, storing and playing back videoinformation and data from a wide selection of video sources have beendeveloped. These have found widespread use among consumers. In additionto conventional video sources like digital video disks (DVD) and VCRs,video from other sources can be sent, stored and played back to a viewerat the viewer's convenience. Video sources include cable, satellite andbroadcast television sources, as well as the Internet. One example of acommercially available storage and playback system is PersonalTelevision (PTV). PTV refers to the viewing of live televisionprogramming in a manner that gives the viewer flexible viewing options,for example, pause and rewind. PTV is also known as Personalized TV,Personal TV Service, File-served Television, Time Delay Recording, TimeShifting and Individualized TV.

One of the video playback features highly desired by consumers isgenerally referred to in the art as “trick play”. The term “trick play”refers to using controls such as pause, instant replay, rewind etc. tocontrol the video presentation. One reason this is referred to as “trickplay” is because these operations can be performed while watching liveTV in near real time. In order to implement such features, video signals(including live TV signals), are typically stored in a memory device,e.g., a hard drive, before being provided to a display unit for displayto the consumer.

Another feature desired by consumers is the ability to stop thepresentation of a show. The stop command differs from the pause command(also referred to as “freeze”). While both commands typically stop thepresentation of moving pictures, the pause command results in display ofa still video frame of the motion picture. The stop command stops thepresentation but does not display a still video frame of the movingpicture. Implementing both the stop and the pause features can beproblematic for recording and playback systems. In most cases, thedecoder in the display device is not under the control of the recorderand playback system. If the recorder/player stops sending frames inresponse to both the stop and pause commands, it is difficult for thedecoder to distinguish between the stop and pause commands. Furthermore,for a pause command, the decoder is typically unable to determine howmany times a particular picture will be displayed. This uncertaintyinterferes with the display order of the pictures being transferred tothe display device.

Therefore, a need exists for improved systems and methods forimplementing the STOP and PAUSE features for such devices.

SUMMARY OF THE INVENTION

The invention provides a video recording and playback system comprisinga video storing and retrieving device coupled to a video display deviceso as to provide the video display device with frames of video data fordisplay. The video storing and retrieving device includes at least onememory capable of storing frames of video data, comprising packetsaccording to a format. The format provides a trick mode indicator. Acontroller is coupled to the memory and controls operations of thememory. A user control device is operable with the controller to allow auser to communicate stop and pause commands to the controller. Aprocessor cooperates with the controller so as to clear the trick modeindicator of at least one retrieved packet in response to the stopcommand. The processor and controller set the trick mode indicator of atleast one retrieved packet in response to the pause command.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example of a recording andplayback system in accordance with an embodiment of the invention.

FIG. 2 illustrates an example of a user operable control device inaccordance with an embodiment of the invention.

FIG. 3 illustrates an example of a hand held remote user operablecontrol device in accordance with an embodiment of the invention.

FIG. 4 is a flow chart illustrating the steps of a method forcommunicating stop and pause commands according to an embodiment of theinvention.

FIG. 5 illustrates a Packetized Elementary Stream (PES) including PESHeader Flag portion and a PES Header Fields according to an MPEG formatsuitable for use with the invention.

FIG. 6 illustrates a Packetized Elementary Stream (PES) including PESHeader Flag portion and a PES Header Fields according to an MPEG formatsuitable for use with the invention.

FIG. 7 is a flow chart for illustrating the steps of a method forreceiving stop and pause commands according to an embodiment of theinvention.

DETAILED DESCRIPTION Definitions and Examples of Applicable IndustryStandards

The following terms are defined as used herein. A “system” refers to anycollection of communicating elements that performs at least onefunction. The term “connection” refers broadly to any transportcapability to transfer information between two or more end points.Accordingly, the invention is applicable to a wide range of physicalnetworks and systems with different realizations of connections,including bidirectional, one way, and point to multi-point (broadcast)connections.

A “command” in the present context means any expression, in anylanguage, code or notation, of a set of instructions intended to cause asystem to perform a particular function either directly or indirectly.Particular functions include those functions performed after either orboth of the following a) conversion from one language, code or notationto another language, code or notation; b) reproduction in a differentmaterial form.

In the context of video playback systems, the following definitions areused herein. The terms “Play” and “Resume” refer to commands that starta presentation, e.g., a movie, from the beginning or resume afterstopping or pausing the movie. The term “Stop” means to Stop thepresentation of the movie. The term “Pause” means to freeze the pictureon the display.

Digital television standards suitable for implementing the inventioninclude Digital Video Broadcast (DVB) standards, as well as thosedescribed by the ATSC DIGITAL TELEVISION STANDARD, Advanced TelevisionSystems Committee, Doc A/53, Sep. 16, 1995.

An example system embodiment employs the MPEG-2 systems and video streamsyntax of ISO/IEC 13818-1 & 2, INFORMATION TECHNOLOGY—GENERIC CODING OFMOVING PICTURES AND ASSOCIATED AUDIO INFORMATION, InternationalStandards Organization, 1995, Sep. 16, 1995. In particular, the ATSCDIGITAL TELEVISION STANDARD describes a model for a hypotheticalancillary services target system decoder for a DTV receiver.

The International Standards Organization provides “Digital Storage MediaCommand and Control (DSM-CC)” standards. This standard provides forcertain client/server operations such as video control (backward, pause,etc.), video transmission, and video service discovery.

In 1998, this standard was extended and became Part 6 of the currentMPEG-2 standard. DSM-CC itself is not developed for datacast, but someparts of DSM-CC, e.g., the Data Download Protocol, DSM-CC sections (apacket encapsulation on top of the PES), and the basic scheme of itsservice discovery, are adopted by both ATSC and DVB datacast standards.

The DVB standards disclose a DVB signal to be carried over a range ofbearer networks. Various standards have evolved which definetransmission over particular types of links. These standards include:DVB-S (Satellite); ETS 300 421 (Digital Satellite Transmission Systems);DVB-T (Terrestrial) ETS 300 744 (Digital Terrestrial TransmissionSystems); Interfaces to Plesiochronous Digital Hierarchy (PDH) networks(prETS 300 813); Interfaces to Synchronous Digital Hierarchy (SDH)networks (prETS 300 814); Interfaces to Asynchronous Transfer Mode (ATM)networks (prETS 300 815); Interfaces for CATV/SMATV Headends and similarProfessional Equipment (EN50083-9).

Each of the above standards is readily available in the literature andthe contents thereof are familiar to those of ordinary skill in the art.

FIG. 1

General System Description

FIG. 1 is a simplified block diagram of a video system 100 according toan embodiment of the invention. As illustrated in FIG. 1, system 100comprises a sender 150 capable of communicating with a receiver 190.Sender 150 provides a packetized data stream 195 to receiver 190 via acommunication link. Packetized data stream 195 transports video images,for example, a plurality of successive video frames comprising a movingpicture for display on a display device 120. Receiver 190 is capable ofreceiving packetized data stream 195 including the video images anddisplaying the images on a display 120. System 100 further includes atleast one user operable control device 160. User operable control device160 is capable of communicating user commands to sender 150 to controlthe display of images on display 120. In one embodiment of theinvention, user operable control device 160 is provided on a front panelof a housing of sender 150. FIG. 2 is an example of a suitable useroperable control device 160 implemented on a front panel of the mainbody of a DVD video recorder/player.

In another embodiment of the invention, user operable control device 160comprises a remote user operable control device, for example, aconventional hand held remote control device. FIG. 3 illustrates aconventional hand held user operable control device according to anembodiment of the invention. Such devices typically communicate usercommands via electromagnetic or infrared radiation to sender 150 as isknown in the art. As those of ordinary skill in the art will readilyappreciate, there exists a wide variety of user control devices ofvarious shapes, sizes and communicating protocols, for controllingrecording and playback systems. The present invention is capable ofimplementation using any of these conventional devices.

In one embodiment of the invention, video system 100 is implemented atleast in part by a personal video recording system (PVR). In anotherembodiment of the invention, video system 100 is implemented, at leastin part, by an integrated television system such as an integrated HighDefinition Television (HDTV) system. Integrated HDTV systems aremanufactured with both the HDTV monitor and HDTV tuner in a single unit.

For purposes of explanation and example, FIG. 1 illustrates one each ofsender 150, receiver 190 and display device 120. In practice however, itis contemplated that any number of such senders, receivers and displayswill be included in system 100. For example, embodiments of system 100include one or more senders 150 communicating with one or more receivers190 within a household or for a plurality of households and subscribers.

As those of ordinary skill in the art will readily appreciate uponreading this specification, the invention is capable of implementationin a variety of video system environments, including non-homogeneoushardware and software environments. Accordingly, an embodiment of videosystem 100 can be described broadly as comprising a client i.e., aconsumer of multi-media content and a server, i.e., an entity thatprovides multi-media content and services. In an embodiment of theinvention, system 100 comprises a distributed system and includesmultiple computing platforms, including video systems (sometimesreferred to as “pumps”) 130 providing video, for example, a video ondemand service. In one embodiment of the invention, sender 150 isimplemented in a “client” of such a system 100. In an alternativeembodiment of the invention, sender 150 is implemented in a server ofsuch a system.

System 100 is capable of implementation in networks that support DigitalStorage Media Command and Control (DSM-CC). DSM-CC is a standard for thedelivery of multimedia broadband services. DSM-CC is defined in part 6of the MPEG-2 standard (MPEG-2 ISO/IEC 13818-6 Extensions for DSM-CC)and is known to those of ordinary skill in the art. DSM-CC embodimentsinclude Hybrid Fiber Coax (HFC) and Fiber to the Curb (FTTC)embodiments. In one embodiment of the invention, HFC network connectionsare realized using an MPEG-2 TS in the downstream (Server to Client)direction and a packet contention scheme in the other direction. Otherembodiments of the invention include FTTC networks realizing connectionsas bi-directional ATM Virtual Channel Connections (VCC's). In anembodiment of the invention, sender 150 is connected to a standard ATMbackbone network while receiver 190 client connects to an access network(such as HFC or FTTC).

User Commands

Regardless of the complexity of the particular implementation, system100 includes a user operable control device 160 capable of communicatinga plurality of playback control commands to sender 150. In oneembodiment of the invention, these commands include “trick mode”commands. The plurality of user commands includes at least two types ofcommands. A first type of command is a type that causes display device120 to stop displaying video images. An example of this type of commandincludes the “stop” command, as generally known in the art. However, theparticular name given to the first type of command is not intended tolimit the invention. The first type of command is any command thatresults in stopping the presentation of video images on display device120. All commands of this type are considered first type commands andare within the scope of the invention, regardless of command name in anylanguage, and regardless of how the stopping is accomplished.

According to one embodiment of the invention, user commands furtherinclude a second type of command. The second type of command is one thatis intended to cause repeated display of the same video image on displaydevice 120. Examples of second types of commands include “pause”, and“freeze” commands. As stated above, the command name is not intended tobe limiting of the invention. Any command that causes repeated displayof the same video image on display device 120, thereby creating theimpression of a still image, is a second type of command.

The first type command and the second type command are intended to havedifferent display effects on system 100. Existing MPEG standards includea format that allows implementing a freeze (pause) command in trickmode. However, most devices presently available with trick modecapability don't continue to send packetized video streams to thedisplay decoder (for example, receiver 190) in freeze mode. Instead,these devices stop sending the MPEG stream. Central Processing Unit(CPU) bandwidth can be conserved in this manner. Nevertheless, thispractice presents difficulties for the decoder in receiver 190. That is,both types of commands result in stopping data input to the framedecoder of receiver 190. In such systems, the frame decoder portion ofreceiver 190 is not typically under control of user operable controldevice 160 and does not directly receive user commands from device 160.Therefore, the frame decoder of receiver 190 cannot determine whichcommand caused the data input to stop.

Inventive Solution

A solution to the problem described above is provided by a method andapparatus according to an embodiment of the invention. According to oneembodiment of the invention, when sender 150 receives a command fromuser operable control device 160, sender 150 responds by providing atleast one corresponding command indicator in packetized data 195.Packetized data 195, including the at least one command indicator, isthen provided by sender 150 to receiver 190. Based upon the at least onecommand indicator, a command decoder of receiver 190 determines thecommand type, and specifically, determines whether the command is afirst type command or a second type command. Therefore, receiver 190 candistinguish between first type and second type commands, and respondappropriately even when packetized data stream 195 stops for bothcommand types.

Detailed System 100 Description

FIG. 1 illustrates logical and functional components of a video system100 according to one embodiment of the invention. The illustratedfunctions and components are capable of implementation in hardware,software and various combinations thereof. Furthermore, the functions ofvideo system 100 as illustrated in FIG. 1 are combinable anddistributable over physical system components. Furthermore, functionsare capable of combining and housing in a single physical enclosure orthey may be distributed over two or more separate enclosures andoperatively interconnected by wires, cables, wireless or other signalconveying means. Regardless of implementation, one embodiment of system100 comprises at least one sender 150, at least one receiver 190, and atleast one user operable control device 160.

Sender 150

General

Sender 150 stores and retrieves moving pictures in any MPEG-2 compliantpacket format. Products and technology, and associated implementationstandards, are available for encoding and transmitting an MPEG-2compliant video stream from a video content source (130, 131 132) tosender 150 over a variety of links. These include: Radio Frequency Links(UHF/VHF); Digital Broadcast Satellite Links; Cable TV Networks;Standard Terrestrial Communication Links (PDH, SDH); Microwave Line ofSight (LoS) Links (wireless); Digital Subscriber Links (ADSL family);and Packet/Cell Links (ATM, IP, IPv6, Ethernet).

Therefore, sender 150 is capable of implementation in a variety ofcommercial systems. These include Personal Video Recorders (PVR),Digital VCRs, Digital Video Recorders (DVR), Digital VideocassetteRecorders, Personalized TV Playback Devices, Digital Disk Recorders,Home Media Servers, Personal Computers, Virtual VCRs, IP MediaAppliances, Digital Network Recorders, Digital Videotape Recorders andVideodisc Recorders and Players.

In one embodiment of the invention, sender 150 includes at least oneinput 241 for receiving a video signal from a video content source.Examples of suitable video content sources include video pump 130,broadcast station 131, cable headend 132 and internet portal 133 andfurther include the sources identified above. The video signal receivedat input 241 includes images to be played back on a display device 120.Commercially available hardware and software is readily available fordelivering video signals from these sources, decoding the signals anddelivering the signal to the input of a recording device.

Sender 150 further includes at least one video storage device 210 forstoring at least a portion of the video images to be played back, and atleast one video output 275 for providing video images, in packetizedformat, to receiver 190 for display. The operation of sender 150 is atleast partially controllable by a user in accordance with the usercommands described herein including at least a first type of command anda second type of command. Sender 150 further includes at least oneprocessor 220 for receiving and encoding user commands including atleast stop and pause commands, from user operable control device 160.

Input 241

As will be appreciated further from the following discussion, input 241is capable of receiving MPEG-2 compliant video signals from at least oneof a variety of video content sources. Suitable video content sourcesinclude, analog and digital TV broadcasting systems, cable and satellitetelevision systems, video and film production systems, multi-point videoconferencing systems, digital video recording applications, real-timevideo transport systems, video monitoring systems, law enforcement andpublic safety applications, video encoding and editing systems andbroadband video on-demand (VOD) systems.

A variety of suitable communication links, including analog and digitalcommunication links exist and are suitable for implementing theinvention. Some examples include, but are not limited to, T1/E1 andEthernet/IP (Internet Protocol) links, broadcast television over theInternet (TV over IP), Integrated Service Digital Networks (ISDN),Public Switched Telephone Networks, cable television networks includingcable head-end links and subscriber networks, satellite links, microwaveand power line communication links, fiber optic links and wirelesscommunication links. In one embodiment of the invention, MPEG compatibleinput video streams are received at input 241. In one embodiment of theinvention, input 241 is capable of receiving a radio frequency carriermodulated responsive to a Motion Picture Experts Group (MPEG) compatiblesignal. Video signals suitable for the invention include digital andanalog signals in compressed and uncompressed formats.

Functions of Sender 150

In one example embodiment of the invention, sender 150 is an integratedDigital Video Broadcast (DVB) receiver capable of receiving,demultiplexing and decoding MPEG signals. In another example embodimentof the invention, MPEG compatible input video streams are received atinput 241. Sender 150 demodulates and processes the received signal inaccordance with MPEG standards.

Examples of MPEG standards suitable for use in system 100 include thoserecommended by ISO/IEC JTC 1/SC29/WG11 (International StandardizationOrganization/International Electrotechnical Commission Joint TechnicalCommittee 1/Sub Committee 29/Working Group 11) for storing video indigital storage media (DSM), for example storage media 212 of sender150. Other suitable standards include the MPEG-2 standard for highdefinition digital broadcasting such as EDTV (Enhanced DigitalTelevision) and HDTV (High definition Television).

In one embodiment of the invention, a carrier modulated according toknown methods includes MPEG compatible signals and is received by sender150 via input 241. Sender 150 tunes to the frequency in which programsto be recorded and played back are multiplexed, and demodulates anderror corrects bit streams corresponding to selected programs. In anembodiment of the invention, sender 150 converts a received bitstreaminto a transport stream (TS) defined by MPEG2 system, and demultiplexesan audio or video PES packet of a program from the TS and outputs a PESpacket to storage subsystem 150.

In another embodiment of the invention, sender 150 receives analogsignals via input 241. In such an embodiment, sender 150 digitizes,encodes and, in some embodiments compresses the analog video signal. Anembodiment of the invention includes a decoder according to theconceptual model for a transport stream system target decoder (T-STD)described in the ISO/IEC 13818-1:1996 (MPEG-2) standard. The MPEG-2conceptual T-STD model comprises an individual system target decoder foreach of the elementary data streams representing the video, audio, andsystem information components of a television program. In thatembodiment, sender 150 receives the television program information andprovides a digitally encoded, compressed video stream compatible forrecording onto storage medium 212 by storage device 210.

In one mode of operation, sender 150 continuously digitizes, compressesand stores video signals received via input 241. For example, sender 150receives programming during a time interval selected by a user. Sender150 compresses and encodes the program video and provides compressedvideo to storage device 210 for temporary storage on storage medium 212.During playback, sender 150 retrieves the compressed data from storagemedium 212 and decompresses and decodes the video.

In yet another embodiment of the invention, sender 150 receives andencodes real time streams of television and video and provides theencoded streams to video storage medium 212 for near real time playbackand viewing on display 120.

In one embodiment of the invention, sender 150 is implemented in a cabletelevision set top box (STB) capable of receiving video images via videoinput 241 from a cable network distribution system. In anotherembodiment of the invention, sender 150 is implemented in a satellitereceiver capable of receiving video images via video input 241 from asatellite downlink, receive antenna or other video signal supplyingmeans.

In one embodiment of the invention, sender 150 is housed in a localtuner/receiver, that is, sender 150 is physically located within abroadcast or cable video tuner/receiver (not shown) at a viewer's site,for example at a viewer's home, along with receiver 190 and display 120.In one embodiment of the invention, sender 150 includes a media player,for example a digital video disk (DVD) player for playing back videoimages from a storage medium such as digital video disk. (DVD) In thatcase, input 241 is in communication with a storage device controller 283that provides images from storage medium 212 in accordance with usercommands.

In an alternative embodiment of the invention, sender 150 is a remotesender, for example, located at a cable headend site, or on board asatellite. In that case, sender 150 is capable of receiving andresponding to commands from a remote user operable control device 160,for example, via a satellite uplink, Out of Band (OOB) communicationschannel, or another suitable communications uplink. At present, trickplay commands are precluded from transmission in a broadcast MPEGstream. However, this is a regulatory constraint and a not a restraintimposed by the available technology for implementing bidirectionalcommunications between user operable control devices and other systemcomponents.

In another embodiment of the invention, system 100 includes InteractiveVideo on Demand (IVOD) capability. IVOD Is an extension of VOD (Video onDemand) in which trick play functions such as fast forward, fast rewind,and pause are implemented. One IVOD system implementation of theinvention includes three components: (1) sender 150 comprising theuser's “Set-top Box”, (2) the network providing input at input 241 (3)servers 130 with archives of movies (or whatever the server is offeringto show.) The consumers communicate with the IVOD server via theirset-top boxes.

Storage Device 210

Sender 150 provides selected, received and processed video signals forstorage by storage device 210. In one embodiment of the invention,sender 150 provides signals in accordance with a DSM-CC (Digital StorageMedia-Command and Control) ISO/IEC standard for the delivery ofmultimedia broadband services. DSM-CC is defined in part 6 of the MPEG-2standard (MPEG-2 ISO/IEC 13818-6 Extensions for DSM-CC). Storage device210 records the audio or video PES packet input onto storage media 212.

In embodiments of the invention wherein system 100 comprises a PersonalVideo Recorder (PVR), sender 150 typically includes the circuits of thePVR that compress the signal of, for example, a live TV show, and savethe show on storage medium 212. Sender 150 subsequently, in oneembodiment with about a 0-3 second delay, provides the stored show toreceiver 190 for display to a viewer. In that case, the viewer iswatching the video from storage medium 212, not directly from theantenna, satellite or cable connection at input 241.

In another embodiment, the PVR receives an already digitally encodedsignal. In that case sender 150 stores the encoded signal. Examples ofencoded video signal sources include, but are not limited to, cableheadends, satellites, digital video broadcast sources, etc.

In one embodiment of the invention, storage medium 212 is temporary, forexample, a buffer memory. Examples of other suitable storage medium 212include semiconductor memories, optical storage media, magnetic storagemedia, and any media capable of storing compressed video signals. Whenplaying back the stored encoded digital signal, sender 150 provides thestored digitally encoded signal to receiver 190. Generally, storagemedium 212 is any storage medium suitable for storing video information.

In one embodiment of the invention, storage medium 212 is suitable forstoring an audio or video PES packet included in a MPEG2 transportstream. Suitable storage media include both removable and fixed storagemedia and digital storage media (DSM), for example, read-only DVD video(or DVD-ROM), write-once DVD-R, recordable/readable DVD-RW (or DVD-RAM),hard disk drives, optical storage media and the like. Exemplaryembodiments of storage medium 212 include DSM implemented as randomaccess memory logic as well as hard disk drives. Commercially availablehardware is adequate for use in the invention.

The DVD video (DVD-ROM) standards support MPEG2 as a moving picturecompression scheme in accordance with the MPEG2 system layer.Furthermore, DVD video standards are configured by adding presentationcontrol data (navigation data) for fastforward, rewind, data search, andthe like. In an embodiment of the invention storage media 212 isformatted according to a standard supporting the UDF Bridge format (ahybrid of UDF and ISO9660) thereby allowing computers to read the storeddata.

Processor 220

In addition to storage device 210, sender 150 includes a storage devicecontroller 283 and processor 220. Commercially available storage devicecontrollers include one or more processors. Typical commercialcontrollers include circuits operatively coupled to input 241, useroperable control device 160 and storage device 210 for controllingrecording and playback of the video information to and from storagemedia 212. For example, in an embodiment of the invention, controller283 analyzes the incoming MPEG video stream and controls writing tostorage medium 212. Processor 220 is representative of a processor thatimplements an inventive command encoder according to an embodiment ofthe invention. Those of ordinary skill in the art will recognize thatthe actual processor employed to implement processor 220 of theinvention is locatable in controller 283, as well as in other circuitsof sender 150. Further, it is anticipated that embodiments of theinvention will implement the functions of processor 220 in a distributedmanner.

User Operable Control Device 160

User operable control device 160 cooperates with processor 220 to permita viewer to control recording and retrieval of video images to and fromstorage media 212. FIG. 2 is an example of a suitable user operablecontrol device 160 implemented on a front panel of the main body of aconventional set top box. Fundamental operations are made by useroperation of control keys 161 and 162. For example, user activation ofSTOP key 162 stops the video presentation. User activation of PAUSE key161 pauses, or freezes, the presentation. Embodiments of the inventioninclude front panels of DVD video recorders incorporating basicoperation keys such as a power switch button, open/close key, playbackkey, stop key, chapter/program skip key, rewind key, fast forward key,recording start button (not shown), and the like.

In one embodiment of the invention, various fundamental operations areperformed by user operation of a remote controller 300 as illustrated inFIG. 3. STOP and PAUSE commands are performed by user activation ofPAUSE key 361 and STOP key 362.

Regardless of the source and device employed to provide the STOP andPAUSE user commands, the invention provides the capability forcommunicating STOP and PAUSE commands from sender 150 to receiver 190.In an embodiment of user operable control device 160, the operation ofthe STOP and PAUSE keys are as follows. When STOP key 162 is pressedduring disc playback or recording, playback or recording is stopped.When PAUSE key 161 is pressed during playback a video frame in theprogram chain currently being played back is displayed as a still image.

According to embodiments of the invention, receiver 190 is capable ofdistinguishing the STOP and PAUSE commands. Further, receiver 190 candistinguish the commands even when sender 150 stops providing videoframes to receiver 190 in both the STOP and PAUSE modes of operation.

User Command Encoding

In a playback mode of operation, storage device 210 provides PES packetsstored in storage medium 212 comprising video packets 195. When sender150 receives a command, for example, a command for normal play or trickplay from user operable control device 160, processor 220 encodes anindication of the user-entered playback command for normal play or trickplay into the PES packets provided by storage medium 212. For example,when the command is a trick play command, controller 284 providespackets from storage medium 212 having a trick play indicator indicatingtrick play mode and sends the packets in video packets 195. Inconventional systems, the indicator is a trick mode bit that istypically set for trick mode data packets. According to the invention, acommand encoder at the output of memory medium 212 determines thesetting of the trick play indicator of packets retrieved from memory. Aprocessor, for example, processor 220 operates on the trick playindicator in accordance with the methods described herein.

FIG. 4 illustrates a flow chart of a processing method employed byprocessor 220 to implement, in cooperation with controller 283, acommand encoding feature according to an embodiment of the invention. Itwill be appreciated that the flow chart of FIG. 4 illustrates but oneadvantageous encoder implementation and that other encoderimplementations may also be used.

According to an example of the invention in use, a user initiates acommand via a user operable control device, for example the device shownin FIG. 1 at 160. According to step 410 the user command is received. Inan embodiment of the invention the command is provided to storage devicecontroller 283. The command is processed by a processor to determine ifthe command is a Stop command, as indicated by step 420. In oneembodiment of the invention, the aforesaid processor is included instorage device 210, e.g., in memory controller 283. In an alternativeembodiment of the invention, the processor is an additional processor,e.g., processor 220. Regardless of where the processor is located, ifthe processor determines the received command is a STOP command, theprocessor encodes a stop command by operating upon at least one packetretrieved from memory medium 212. In one embodiment, in response to aStop command, processor 220 ensures a trick mode flag in at least one ofthe packets retrieved from memory medium 212 is cleared, and forwardsthe at least one packet including the cleared flag to receiver 190.

On the other hand, if the processor determines the command issued by auser is not a STOP command, the processor further determines if thecommand is a PAUSE command as indicated at step 430. If the processordetermines the command is not a PAUSE command the processor proceedswith another operation as illustrated by step 440. In that case, nofurther action is to be taken by the processor regarding the trick modeflag and the trick mode field of the PES packets. Other operationsinclude executing a command other than stop or pause. The process end isillustrated at 499.

If the processor determines the command issued by a user is a PAUSEcommand, the processor encodes the pause command in a retrieved packetby setting a trick mode flag of a retrieved packet to 1 and furtherinsures the trick mode field is set to indicate a freeze mode, asillustrated in step 450. In one embodiment of the invention, thetrick_mode_control field is set to indicate freeze mode according to thesettings shown in Table 2 below.

In one embodiment of the invention, when the Pause command is generatedby the user operable control device, sender 150 obtains Intra picture (Ipicture) information from storage device 210 and instructs transfer ofthe I picture data to the PES packets for repeated display of an I frameon display 120.

Packetized Data 195

FIG. 5 illustrates a format of an example packet 500 of video packets195 according to an MPEG compliant embodiment of the invention. Examplepacket 500 is organized into a plurality of fields 510-590. According toan MPEG compliant packet format, a Primary Elementary Stream (PES)packet data block field 590 is followed by a PES header field 580, a PESHeader length field 570, a PES header flag field 550, and other fields540-510, as described in MPEG packet format specifications readilyavailable in the art.

PES header flag field 550 comprises a plurality of indicator fields,i.e., flags 551-562. In particular, in an embodiment of the invention,Trick Mode TM flag 559 indicates the operating mode of storage device210, as shown in Table 1.

TABLE 1 Trick Mode (559) Indicates the presence of an 8(DSM_trick_mode_flag) bit field describing the DSM (Digital StorageMedia) operating mode: 1 - Field is present. 0 - Field is not present.(For broadcasting purposes, set = 0.)

FIG. 6 illustrates PES header fields 580 of packet 500. As shown, fields580 comprise a plurality of fields 581-586 representing the PresentationTime Stamp (PTS), Decode Time Stamp (DTS), and Elementary Stream ClockReference (ESCR), ES rate of twenty two bits, additional copyinformation of seven bits, previous PES Cyclic Redundancy Check (CRC) ofsixteen bits and PES extension control.

In particular, a DSM trick mode control field 582 comprises eight bitsof data.

DSM trick mode field 582 is used to indicate that a video streamoriginally stored on recording media (e.g., 212 of FIG. 1) is subjectedto trick mode reproduction and differs from the corresponding source bitstream received at input 241 by sender 150. Table 2 describesDSM_trick_mode field 582.

TABLE 2 DSM_trick_mode An eight bit field indicating the nature of theinformation encoded. The field is further partitioned as follows:trick_mode_control (3 bits), field_id (2 bits), intra_slice_refresh (1bit), and frequency_truncation (2 bits). trick_mode_control Indicatesthe nature of the DSM Mode: 000 - Fast Forward 001 - Slow Motion 010 -Freeze Frame 011 - Fast reverse 1xx - Reserved.Receiver 190

Receiver 190 includes an input 194 for receiving packetized data 195including a command indicator from sender 150. Receiver 190 processesthe video data in the packetized data stream and converts the video datato a form suitable for presentation on display device 120.

Decoder

Receiver 190 includes a processor 184 for implementing a decoder 252 fordetermining if a user has given a Stop or Pause command to sender 150.Processor 184 is informed by means of a 1 bit flag (DSM_trick_mode_flag)in the PES packet header indicating that the bitstream is reconstructedby DSM in trick mode, as described above, and in particular, as modifiedby sender 150 according to the principles of the invention. When theDSM_trick_mode_flag is set, an 8 bit field (DSM_trick_modes) follows.According to one embodiment of the invention, this field is encodedaccording DSM_trick_modes semantics defined in the ISO/IEC 13818-1.D.11.1, and further encoded by sender 150 of the invention to indicateStop and Pause commands. Processor 184 decodes the bitstream anddisplays it according to DSM_trick_mode, if any, identified in the 8 bittrick mode field (582 of FIG. 6). According to one embodiment of theinvention, If the DSM trick mode field contains a PAUSE code, a videodecoder of receiver 290 decodes the picture and displays the latestreceived I frame until the next picture is decoded.

In that way, processor 184 comprises a decoder 252 for determining auser command based on a command indicator. Processor 184 makes thisdetermination, at least in part, by detecting the state of the commandindicator in the packetized data stream. Receiver 190 cooperates withdisplay device 120 to display video images in accordance with the usercommand determined by processor 184.

Therefore, processor 184 implements a method for decoding video datapackets so as to distinguish a stop command from a freeze command. FIG.7 is a flow chart that illustrates exemplary modes of operation ofreceiver 190 as it displays the video corresponding to packetized data195. It will be appreciated that the flow chart of FIG. 7 illustratesbut one advantageous implementation and that other implementations areenvisioned.

As discussed above, typical displays include a video decoder 185.However, the invention further includes an apparatus and method fordecoding Stop Pause commands based on the status of the TM flag inreceived packets. A processor 184 has access to the packetized dataprovided by sender 150 such that it can provide the data containedtherein to a video stream decoder. Similarly, processor 184 also hasaccess to the frame index data structure such that processor 184 can usethis information to facilitate implementation of TrickPlay of the videostream data.

FIG. 7 Receiving

FIG. 7 is a flow chart illustrating a method for receiving trick modecommands according to one embodiment of the invention. The method beginsat step 710 when receiver 190 is receiving video data 195 from sender150 as illustrated in FIG. 1.

According to step 720, receiver 190 checks frame decoder 252 todetermine if frames are being decoded. As long video data packets 195are decoded, processor 184 updates a trick mode flag 188. Trick modeflag 188 is implemented in receiver 190. In one embodiment of theinvention, trick mode flag 188 is a specified bit in a memory ofreceiver 190.

According to step 740, processor 184 updates receiver trick mode flag188 to reflect the state of the trick mode flag of respective receivedpackets. As long as the trick mode flag field of the received packets isset, receiver trick mode flag 188 is set and the bits in trick modefield of data stream are decoded. In that case, processor 184 determinesthe designated trick play based on the contents of the bits in thefield, and an indication of the trick mode, i.e., Fast Forward, SlowMotion, Freeze Frame and Fast Reverse, is provided via mode indicator183 as indicated by step 744.

On the other hand, if data input to frame decoder 252 stops, step 720continues with step 722. That is, when data is not present, the lasttrick mode flag 188 is checked. If the last trick mode flag 188 is set,mode indicator 183 is checked. If mode indicator 183 indicates “freezeframe”, a Pause command is detected and a last received frame of data isrepeatedly displayed on display 120. In one embodiment of the invention,the last received Intra coded reference frame (I frame) is repeatedlydisplayed.

In the event no data is present as per step 720 and the “last trickmode” indicator 188 is not set (i.e., the flag is cleared), then a Stopcommand is detected. In that case, a last received frame of data is notrepeatedly displayed on display 120.

In light of the foregoing description of the invention, it will berecognized that the present invention can be realized in hardware,software, or a combination of hardware and software. Communicatingaccording to the present invention can be realized in a centralizedfashion, or in a distributed fashion where different video processingelements are spread across several interconnected systems.Advantageously, in such an entertainment system, the information filecan be used to communicate information between independently andremotely located MPEG decoders. Any kind of computerized or digital MPEGprocessing system, or other apparatus adapted for carrying out themethods described herein, is suited.

Although the present invention as described herein contemplates a CPU122 of FIG. 1, a typical combination of hardware and software canfurther include a general purpose computer system with a computerprogram that, when being loaded and executed, controls the digital videorecording and playback system similar to the control section 120 of FIG.1, such that it carries out the methods described herein. The presentinvention can also be embedded in a computer program product whichcomprises all the features enabling the implementation of the methodsdescribed herein, and which when loaded in a computer system is able tocarry our these methods.

The description above is intended by way of example only and is notintended to limit the present invention in any way, except as set forthin the following claims.

1. A method for communicating stop and pause commands in a videorecording and playback system, comprising the steps of: in response to apause command, setting a trick mode indicator of a last frame of videodata to be displayed to indicate a freeze trick mode; and in response toa stop command, clearing a trick mode indicator of a last frame of videodata to be displayed.
 2. The method of claim 1, further comprisingcommunicating said video data to a display device.
 3. The method ofclaim 1, wherein said video data comprises packetized data.
 4. Anapparatus for a video recording and playback system, comprising: astorage device for storing at least video data; a controller incommunication with said storage device for controlling the selection ofstored video data to be displayed; a processor in communication withsaid controller, said processor configured to perform the steps of: inresponse to a pause command, setting a trick mode indicator of a lastframe of said video data to be displayed to indicate a freeze trickmode; and in response to a stop command, clearing a trick mode indicatorof a last frame of said video data to be displayed.
 5. The apparatus ofclaim 4, wherein said trick mode indicator comprises a trick mode flagof an MPEG-2 compliant video packet.
 6. The apparatus of claim 4,wherein said video data comprises frames of video data having a packetformat.
 7. The apparatus of claim 6, wherein said packet formatcomprises an DSM-CC compliant video packet format.
 8. The apparatus ofclaim 4, wherein said packet format comprises an MPEG-2 compliant videopacket format.
 9. The apparatus of claim 4, wherein said apparatuscomprises a personal video recording device.
 10. A video systemincluding: a sender including at least an input for receiving video dataand an output for communicating packetized video data to a receiver;said sender responsive to user commands; said receiver including atleast an input for receiving said packetized data and an output forproviding corresponding video images formatted for display; and a useroperable control device for communicating said user commands to saidsender, said commands including at least a pause command and a stopcommand; wherein in response to a received pause command, said sendersets a trick mode indicator of a last frame of said packetized videodata to be communicated to said receiver to indicate a freeze trick modeand in response to a received stop command, said sender clears a trickmode indicator of a last frame of said packetized video data to becommunicated to said receiver; and wherein in response to adetermination by the receiver that packetized video data is no longerbeing received, the receiver examines a trick mode indicator of a lastframe of received video data and if a trick mode indicator of the lastreceived frame of video data indicates a freeze trick mode, the lastreceived frame of video data is repeatedly displayed on a display, andif a trick mode indicator of the last received frame of video data isclear, the display of frames of said video data on the display isstopped.
 11. The system of claim 10, further comprising a display fordisplaying frames of said video data.
 12. The system of claim 10,wherein said system comprises a high definition television system. 13.The system of claim 10, wherein said sender comprises a personalrecording device and said receiver comprises an MPEG compliant videodecoder.